I hate to say it...EBay. It has become the hunting grounds for collectors of all kinds. Ebay isn't just a junk market anymore. There are lots of high-end collectables thee now and it's probably one of the largest markets in the world, so you'll get a lot of attention. I would also twitter your listings to increase views and prospective buyers. It may take you awhile to get a reputation going, so you might want to start with your lower priced quilts first. Also, make sure that you convey that you are selling collector's quality and not some cheapy goods.
~ Cindy